The invention relates to a propelling nozzle for a flying aggregate equipped with combined turboramjet engines, in which a variable course of the contour of the nozzle is in each case developed between upper and lower primary and secondary flaps which are sealingly movably guided at parallel wall surfaces of a square nozzle housing, the primary flaps, in each case, being pivotally connected upstream to the nozzle housing, and the secondary flaps, in each case, being pivotally connected to pivots of the primary flaps situated on the side facing away from the nozzle flow and with sections which are essentially concentric with respect to these pivots, and being selectively movable into and out of the primary flaps in an aerodynamically surface-covering manner. The invention also relates to a process for adjusting this propelling nozzle as a function of different flying speeds and is an improvement to the invention described in commonly assigned German Patent Application P 39 01 487, corresponding U.S. Pat. application Ser. No. PCT/DE90/00020, filed Jan. 16, 1990.
It was an object of this above-noted German application to provide a propelling nozzle which, as a supersonic expansion nozzle, makes it possible to achieve an adjustment of the cross-sectional surface of the nozzle throat which is advantageous over a wide operating range without causing compression shocks. In particular, the nozzle flow was to be adapted to a large environmental pressure range (extremely different flying altitudes) with an optimal thrust.
This object was achieved by the above-noted combination of features.
On this basis, it is an object of the present invention to use such a nozzle for a combined turboramjet engine in which the two engines are constructed separately of one another with separate outlet ducts.
According to the invention, this object is achieved in that the gas turbojet engine and the ramjet engine are arranged axially above one another, and their outlet ducts end with rectangular cross-sections, and a partition is provided between both outlet ducts which extends in the downstream direction to the narrowest cross-section of the propelling nozzle, and the nozzle flaps, in the transition area from the primary flaps to the secondary flaps, on both sides, being placeable against its edge area in an advantageous manner with respect to the flow.
A principal advantage of this arrangement according to the invention is that, in the turbo-operation, in a simultaneous turbo-operation and ramjet operation and in the exclusive ramjet operation, the optimal narrow cross-section of the nozzle as well as the nozzle divergence can easily be adjusted in an optimal and low-loss manner. It is also an important advantage that the same nozzle arrangement may be used for all three operating methods without having to accept compromises with respect to efficiency. Advantageously, the turbojet engine and the ramjet engine may be installed and also operated separately from one another, while nevertheless the same propelling nozzle may be used for both arrangements. Up to now, this had been considered feasibly only for integrated turboramjet engines in which the ramjet combustion chamber is simultaneously the turbo-afterburner chamber; i.e., wherein the gas turbo-engine and the ramjet engine are quasi-concentrically arranged with respect to one another. It is also an advantage of preferred embodiments of the invention that the partition causes a transverse stiffening of the propelling nozzle.
In a further development according to the invention, the end edge of the partition is extended u in the direction of the top side of the partition making it possible to achieve a contour from the bottom side of the partition to the top side of the secondary flap which is advantageous with respect to the flow when the upper pair of nozzle flaps (turbo-operation) rests against it.
An advantageous further development of the invention provides that the partition is movable which, in a preferred embodiment of the invention is achieved by the fact that the partition can be retracted in an axial upstream direction. However, advantageously, the partition can be swivelled around a transverse axis situated in the wall plane, or the partition comprises a first upstream rigid section and a second pivoted partition section connected to it in an advantageous manner with respect to the flow. This arrangement has the advantage that, for the adjustment of the narrow cross-section and the nozzle divergence, the two nozzle flap pairs may have a considerably more restricted adjusting range since part of the kinematic adaptation is taken over by the movable partition and the movable partition section. In comparison to a rigid partition, as a result of the smaller swivel range of the nozzle flap pairs, a transition into its extreme positions can also be achieved that is more advantageous with respect to the flow.
In a preferred further development of the invention, devices for locking the partition in discrete positions ar provided on both sides in the lateral nozzle walls of the rectangular nozzle. These may, for example, be constructed as pins which can be moved out in the area of the end edge and which can be moved into corresponding recesses of the partition. As a result, the very high pressure forces (approximately 40 t) are absorbed and the swivel arrangement is relieved. Preferably, three different discrete positions are provided, specifically a first position with a maximum positive slope for the turbo-operation; a second, approximately horizontal position for a simultaneous turbo-operation and ramjet operation; and a third position with a maximum downward slope for an exclusive ramjet operation. If required, intermediate positions may also be adjustable, or the movable partition section may even be adjustable continuously. It is also possible to provide only two discrete positions between which a changing-over takes place. The change-over from one position to another position preferably takes place during a simultaneous turbo-operation and ramjet operation, in which case an approximately identical pressure is adjusted on both sides of the movable partition section, and the change-over may take place by a swivel arrangement with small dimensions.
A further advantageous development of the invention provides that closable reversed thrust openings are provided which preferably are arranged in the outlet duct of the turbo-engine. Thus it becomes possible to bring the two nozzle flap pairs simultaneously into a sealing contact with the partition, and thus close both outlet ducts. In this case, the turbo-exhaust gases can be blown out by way of the reversed thrust openings against the propulsion direction, and thus cause a braking of the airplane after the landing.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.